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OBD fault code guide

P0141 Code Meaning UK

P0141 means “Oxygen Sensor Heater Circuit Malfunction Bank 1 Sensor 2”. In plain English, the engine computer has detected a problem with the heater circuit inside the rear oxygen sensor, usually the sensor fitted after the catalytic converter. This heater helps the sensor warm up quickly so the emissions monitoring system can work properly.

📅 Updated June 2026 🇬🇧 UK diagnostic guide 🛠 Rear oxygen sensor heater fault
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Quick answer

What does P0141 mean?

P0141 means the rear oxygen sensor heater circuit for bank 1 sensor 2 is not working as expected. Bank 1 sensor 2 is normally the oxygen sensor after the catalytic converter. Its job is mainly to monitor catalyst performance, not control fuelling like the front sensor. The heater circuit helps it reach working temperature quickly so the ECU can monitor emissions properly.

Most likely area

Rear oxygen sensor heater, fuse, wiring, connector, earth, power supply or ECU heater control.

Urgency

Usually moderate if the car drives normally, but it should be repaired because it affects emissions monitoring.

MOT risk

Can affect emissions monitoring and engine warning light status.

Code meaning

P0141 — O2 Sensor Heater Circuit Bank 1 Sensor 2

The full description is usually P0141 O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 2. “Sensor 2” normally means the oxygen sensor fitted after the catalytic converter. This rear sensor helps the ECU monitor how well the catalytic converter is working.

The heater circuit is an electrical circuit inside the sensor. It warms the sensor quickly after start-up. If the heater element fails, the fuse blows, or the wiring is damaged, the ECU can store P0141.

Mechanic view

Why P0141 is different from a catalyst fault

P0141 is not the same as a failed catalytic converter. It is a heater circuit fault for the rear oxygen sensor. However, because the rear sensor helps monitor the catalyst, ignoring P0141 can make catalyst diagnosis harder later.

If a car has both P0141 and P0420, I would normally repair the rear oxygen sensor heater circuit first, clear the codes, then road test and see what returns.

Symptoms

Common symptoms of a P0141 code

P0141 often causes fewer driveability symptoms than front oxygen sensor faults, but it still matters for emissions monitoring and MOT preparation.

Engine management light

A steady engine warning light is the most common sign of a stored P0141 fault.

No obvious symptoms

Many cars still drive normally because the rear oxygen sensor is mainly used for catalyst monitoring.

Emissions readiness issue

The car may struggle to complete emissions readiness monitors if the rear sensor heater is faulty.

Poor emissions result

A faulty emissions monitoring circuit can contribute to MOT or garage emissions concerns.

Related catalyst codes

P0141 may appear with catalyst efficiency codes such as P0420 on some vehicles.

Repeat warning light

The engine light may return quickly after clearing if the heater circuit is open or shorted.

Common causes

What causes a P0141 fault code?

P0141 is usually caused by a rear oxygen sensor heater fault or an electrical issue in the heater circuit.

Very common

Faulty rear oxygen sensor heater

The heater element inside the rear oxygen sensor can fail with age, mileage and exhaust heat.

Electrical

Blown oxygen sensor heater fuse

A heater feed fuse may blow if there is a short circuit or damaged sensor wiring.

Wiring

Heat-damaged wiring

Rear oxygen sensor wiring can suffer from exhaust heat, road debris, corrosion and poor routing.

Connector

Corroded rear sensor connector

Water, salt and road dirt can affect the connector underneath the vehicle.

Circuit

Open or short circuit

A broken wire or shorted heater circuit can stop the sensor heater working.

Earth fault

Poor ground connection

A weak ground can prevent the heater circuit from completing properly.

Previous repair

Incorrect oxygen sensor fitted

Poor-quality or incorrect sensors can cause repeat heater circuit codes.

Exhaust work

Sensor wiring disturbed

Exhaust or catalytic converter repairs can pull, twist or trap the sensor wiring.

Rare

ECU heater control fault

Rare, but possible after the sensor, fuse, wiring and connector have all tested correctly.

Diagnosis

How a garage should diagnose P0141

✅ Scan all stored, pending and permanent codes.

✅ Record freeze frame data before clearing anything.

✅ Confirm the code refers to bank 1 sensor 2, not the front oxygen sensor.

✅ Inspect the rear oxygen sensor wiring and connector underneath the vehicle.

✅ Check for exhaust heat damage, rubbing, trapped wiring or corrosion.

✅ Check the heater circuit fuse and power supply.

✅ Check ground control and wiring continuity.

✅ Measure heater resistance where manufacturer data is available.

✅ Replace the rear oxygen sensor only when circuit testing supports it.

Avoid this mistake

Do not replace the catalytic converter for P0141

P0141 is a rear oxygen sensor heater circuit fault. A catalytic converter may be checked if there are separate catalyst codes, but P0141 alone does not mean the cat has failed.

The first job is to test the rear sensor heater circuit. If that circuit is dead because of a fuse, wiring or sensor heater problem, replacing the catalyst will not fix P0141.

UK repair cost guide

How much does P0141 cost to fix in the UK?

Costs vary by vehicle, rear oxygen sensor access, corrosion, part quality and labour rate. These are rough UK guide prices only.

Diagnostic scan and circuit test

Usually around £40–£120 depending on how much wiring and access testing is included.

Rear oxygen sensor replacement

Often around £80–£250 depending on access, sensor quality and whether the old sensor is seized.

Fuse or power repair

Can be low cost if simple, but the cause of a blown fuse must still be checked.

Connector repair

Under-car connectors can corrode, so repair cost depends on access and loom condition.

Wiring repair

Heat-damaged or trapped wiring may take longer to trace and repair properly.

Emissions check

Useful after repair if the vehicle had MOT emissions issues or catalyst-related codes.

Safe driving advice

Can you drive with a P0141 code?

If the car drives normally and the engine light is steady, short careful driving may be possible. However, P0141 should not be ignored because the rear oxygen sensor heater helps the emissions monitoring system work correctly. Leaving it can cause repeat warning lights and MOT readiness problems.

✅ Lower risk: steady engine light, normal performance, no smoke and no misfire.

⚠️ Medium risk: repeat engine light, poor emissions readiness or related catalyst codes.

🚫 Higher risk: misfire, smoke, major power loss, strong fuel smell, overheating or flashing engine light.

Real experience

What I would check first

On a real car with P0141, I would first look underneath at the rear oxygen sensor wiring. This area is exposed to heat, water, salt and road dirt, so wiring and connectors can suffer.

If the wiring looks good, I would test the heater power and ground. If supply and ground are present but the heater resistance is wrong, the rear oxygen sensor is a strong suspect.

MOT implications

Will P0141 fail an MOT?

P0141 can lead to an MOT failure if the vehicle has an emissions-related engine warning light, poor emissions, smoke or an emissions monitoring fault that affects the test. The rear oxygen sensor heater helps the vehicle monitor catalyst performance correctly.

Emissions monitoring

A faulty rear sensor heater can stop the emissions system completing checks properly.

Warning light issue

An engine warning light linked to emissions should be fixed before MOT.

Catalyst diagnosis

P0141 can make catalyst efficiency diagnosis less reliable until the sensor circuit is repaired.

Engine light MOT guide Common MOT failures
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Browse more OBD fault code guides

P0141 is one common rear oxygen sensor heater and emissions-related diagnostic trouble code. For more common codes, meanings, symptoms, repair costs and MOT implications, use the main Motor Vehicle Expert fault-code hub.

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Frequently asked questions

Frequently Asked Questions About P0141

Find answers to common questions about P0141 rear oxygen sensor heater faults, driving safety, repair costs and MOT implications.

What does P0141 mean?

P0141 means the engine computer has detected a fault in the oxygen sensor heater circuit for bank 1 sensor 2. This is usually the rear oxygen sensor fitted after the catalytic converter.

Can I drive with a P0141 code?

Short careful driving may be possible if the car runs normally and the engine light is steady, but P0141 should not be ignored because it can affect emissions monitoring and MOT readiness.

Will P0141 fail an MOT?

P0141 can lead to an MOT failure if it causes an emissions-related engine warning light, poor emissions, smoke or a problem with the emissions monitoring system.

What causes a P0141 code?

Common causes include a faulty rear oxygen sensor heater, blown fuse, damaged wiring, corroded connector, open circuit, short circuit, poor earth, exhaust heat damage or ECU heater control issue.

How much does P0141 cost to fix in the UK?

A diagnostic check may cost around £40 to £120. Rear oxygen sensor replacement may cost around £80 to £250 depending on access and part quality, while wiring or connector repairs vary.

Is P0141 the same as P0135?

No. P0135 usually refers to the front oxygen sensor heater circuit on bank 1 sensor 1, while P0141 usually refers to the rear oxygen sensor heater circuit on bank 1 sensor 2.

About this guide

Based on practical mechanic-style diagnostic experience

Motor Vehicle Expert publishes practical UK vehicle guidance based on real-world mechanical knowledge and hands-on diagnostic experience. This P0141 guide is written to help drivers understand rear oxygen sensor heater circuit faults before replacing parts unnecessarily.

Fault codes should always be treated as a starting point for diagnosis. If your car has a flashing engine light, severe misfire, smoke, overheating, strong fuel smell or major power loss, stop driving and get professional help.